Nigeria experienced a sharp drop in power after a gas pipeline rupture caused six power stations to halt operations temporarily, the electricity grid operator said, underscoring the chronic instability of the country's power infrastructure.

The Transmission Company of Nigeria (TCN), the grid operator, said late on Sunday that the rupture on June 15 and "technical issues" at Shell gas wells the following day led to the stations being shut down in a measure known as load shedding aimed at averting a wider collapse.

Nigeria's creaking power grid is often blamed for hobbling growth in west Africa's largest economy.

Nigeria privatised most of its power sector in 2013 but retained control of dilapidated monopoly grid operator TCN. Most of Nigeria's power generation is from thermal power stations that use gas.

"With a total loss of 1,087.6 megawatts (MW) into the grid, the transmission system has become quite fragile and TCN is working hard to avert a collapse of the system by engaging in load shedding," said TCN spokeswoman Ndidi Mbah in a statement.

Nigeria's power output stands at around 4,000 MW, according to the Nigeria Electricity System Operator. Total power generation capacity is about 7,000 MW but if plants operated at full tilt the transmission network could not handle the power.

Country's frequent blackouts

TCN, in its statement, said Shell had resolved the problem with its gas wells.

It was not clear whether the six power plants affected - which include the Azura, Ihovbor and Egbin power stations, all in the south of the country - had resumed operations. TCN's spokeswoman did not immediately respond to calls and text messages on Monday.

A spokesman for the Nigerian National Petroleum Corporation (NNPC), which owns and operates the gas pipelines, said it was not clear what caused the rupture.

"We are discussing with the managing director of Nigerian Gas Company to ascertain what really happened and what could quickly be done," said the spokesman, Ndu Ughamadu, on Monday when asked whether the problem with the gas pipeline was ongoing.

The impact of the outage is unclear. Many businesses and households in Nigeria use their own power generators, which are run on fuel and often costly, as a backup for the country's frequent blackouts.